dbind() of a named list

[benthestatistician]

When dbind()'s first arg is a named list of ISMs, it should used those names as the levels of @groups in the BISM it produces.

[benthestatistician]

A special bonus to this enhancement would be that when it's given a list of ISM and BISMs, it pulls levels for the non-BISM ISMs from the list names while pulling levels corresponding to the BISMs from levels of those BISMs' @groups.